A heat pump type cooling/heating apparatus comprises a coolant injection path and a gaseous coolant adjustment valve. The coolant injection path may be split between a cascade heat exchanger and an evaporator of a low-temperature refrigeration cycle to inject coolant into a low pressure side compressor, or between a water coolant heat exchanger and cascade heat exchanger to inject coolant into a high pressure side compressor of a high temperature refrigeration cycle. The gaseous coolant adjustment valve may be provided in the coolant injection path and is adjusted to correspond to a load of a